Wheel dresser and method of dressing grinding wheels



J. SNEED Dec. 15, 1942. 2,305,115

} WHEEL DRESSER AND METHOD OF DRESSING GRINDING WHEELS Filed March, 9,1959 2 Sheets-Sheet 1 I! w W miwun I JQ/f/V sun-p BY z 7 ATTORN Dec. 15,1942. J. SNEED 2,305,115

WHEEL DRESSER AND METHOD OF DRESSING GRINDING WHEELS 2 Sheets-Sheet. 2

Filed March 9, i959 INVENTO. JOHN s/vp v %V6r% ATTORNEYS Patented Dec.15, 1942 WHEEL DRESSER- AND METI IOD 0F DRESS- ING GRINDING WHEELS JohnSneed, Grosse Pointe Shores, Mich. Application March 9, 1939, Serial No.289,797

-13 Claims. (Cl. 125- 11) This invention relates to a method and meansof dressing grinding wheels and the tools and other instrumentalities tobe shaped, dressed, or formed thereby or therewith. More especially thisinvention is concerned with obtaining great accuracy in dressinggrinding wheels (and the corresponding work) in which theface of thewheel and/or work is to be given an irregular or non-lineal contour,along with a method and apparatus that is simple, economical, foolproofand inherently free from tendency to err or fall out of adjustment.

Prior to my invention, the art of dressin grinding wheels has beenattended with elaborate mechanisms and costly methods of forming theworking contour of the wheel to correspond to the desired or intendedshape. Moreover, the

prior art left much to be desired in speed of operation, ease ofre-dressing, accuracy of dressing and re-dressing, and generalsimplicity of means and economy of operation.

in the position and general relationship of parts in which the followeris given the contour cor responding to and aligned with the contour ofthe dressingtool.

In Figure 3 the parts illustrated in Figure 1 are shown in operativeposition with relation to a grinding wheel to be dressed along withappropriate supporting means for the wheel and illustrative clampingmeans and other support for the base block.

Figure 4 is an illustrative plan view showing on the left side the baseblock, carrier block with attendant devices and mechanisms in relationto a dressed grinding wheel, and showing on the right side anillustrative piece of. work to be dressed in its relation to thegrinding wheel,

Within the objects of my invention I have sought to cure the defectsexisting in the art as mentioned in part above, and to provide a meth-0d and means of dressing grinding wheels having low initial cost andunkeep, great and continuing accuracy inherent in its design andoperation, ruggedness and simplicity in its construction and operation,all to the ultimate end of faithfully and consistently reproducing inand through the dressing of a grinding wheel the shape, contour or formsought to be transferred or reproduced in the tool or otherinstrumentality to be dressed or formed.

Other objects and advantages of my invention will become evident fromthe following description of a preferred form of an embodiment of myinvention along with exemplary structures,

I.am aware of the disclosure and claims of U.- S. Patent No. 2,137,690issued November 22; 1938,

and believe myself to be the first and original inventor of so much ofthe subject matter there- .of as I have disclosed and claimed in thisapplication. I

In the drawings Figure 1 is a perspective view of the base block,template, carrier black, dressing tool and feeler or follower associatedtogether in substantially the relation and position for the wheeldressing operation.

Figure 2 illustrates the carrier block with its dressing tool and feeleror follower beinz supported in relation to a second grinding wheelalthough out of contact therewith.

Figure 5 is a plan view of an illustrative form of' template.

Figure 6 is a partly diagrammatic elevation of the mechanism and partsillustrated in Figure 4 showing the relation thereof in a verticalplane.

To illustrate a manner in which my invention may be put into practicethere is shown in. Figure 5 a template T, having formed on one facethereof between about the points ll-the irregular tion. In Figure 4, forexample, it will be seen that I have shown the contour of the face ofthe grinding wheel precisely corresponding to the contour of thetemplate T as a result of the operations to be described.

Preferably the template T comprises a thin hardened steel plate with itsrearward edge a preferably ground straight and true to facilitate itssupport during the time its contour l-i is .being formed. The templatealso preferably has holes 3 by virtue of which it may be fixedly andrigidly secured to the base block B, see Figure 1,

by appropriate clamping means 5 which may conveniently compriseshouldered studs with clamping nuts arranged to hold the body of thetemplate-preferably in a true'horizontal plane in fixed parallelrelation to the block B. Preferably theholes 3 are equally spaced fromthe true back edge of-the template, and are pro!- erably aligned to beparallel with the adjacent verticalface of the ,base block B, wherebythe template T or any other template having similar characteristics withthe same or different contours l-l, will always take the same positionwith respect to the base block B, and the wheel to be dressed, forvarious or succeeding operations. Preferably the true back edge of thetemplate will lie parallel to the axis of the wheel to be dressed.

The base block B is preferably formed of hardened steel or othersubstantial material, preferably having considerable mass and generalruggedness, whereby to be substantially unyielding and inflexible in itsintended use and to present and maintain the bearing points or areas inits upper surface 6 in a true geometric plane surface throughout itsoperation in carrying out the objects of my invention. The upper surface8 of the block B may preferably be grooved with relatively smalllongitudinally extending grooves 1,

, which are provided for the purpose-of preventing the collection oraccumulation of dust. grit or any extraneous material on the supportingsurface whereof, or more particularly on the portions of the surfacelying in the plane which in the aggregate comprises the true planularsupporting surface 6 of the top face of the block B.

Preferably the side faces of the block B lie at right angles to the topsurface 6 and at the right angles to each other, and are grooved as at 8for the reception of clamping blocks 9, see Figure 3, whereby the blockB may be fixedly secured to any convenient support 10, which I haveshown for illustration in Figure 3. By way of example of a useful sizeof the block B the same may conveniently be about 8" to 10" square and2" or 3" deep where grinding wheels up to about 10" diameter are to bedressed. In the dressing of larger or smaller wheels, the block B andassociated parts may, of course, be similarly enlarged or reduced insize, while retaining the characteristics essential to the practice ofmy inven tion.

Resting upon the block B as'shown in Figure 1 is a carrier block C, thesize of which in relation to the block B and the wheel W may preferablybe about that shown in the drawings. This block may be conveniently madeof material similar to that of the block B, and preferably comprises asolid block of hardened steel of substantial mass and stability so as tobe substantially unyielding and inflexible in carrying out its part inthe practice of my invention. The weight of the block C is preferablysufficiently great to tend to cause the block C to lie firmly thoughslidably upon the block B and be inherently free from tendency to tipwithout manual support during dressing operations.

As shown in Figure 1 the block C receives and firmly embraces near itsupper end a dressing tool D carrying a diamond or other hardened wheelcutter II. .The dressing tool D preferably has its body embraced withinthe body of the carrier block C in a relatively snugly fitting hole,wherein it may be fixedly though removably secured by such means as setscrews l2. Embraced in a similar mannerwithin the carrier block C is afollower or feeler F similarly, securely and removably held in the lowerportion of the carrier block C with the aid of set screws I3. Thedressing tool D and the feeler F, as shown, are in vertical alignment,preferably both having their bodies lying parallel and in about the samevertical plane and extending at substantial right angles to the rearface H of the carrier block C, see also Figure 4. As shown in Figure 1'the carrier block C has its lower end supporting face l5, see alsoFigure 2, grooved with its grooves arranged to lie generally transverseto the grooves of the block B, so that the block C will rest upon theblock B on a plurality of small surfaces defined by the respectivegrooves in the'respective blocks, which surfaces all lie in a truegeometric plane. The supporting face l5 of the block C,

geometric plane disposed at right angles to the back face I of thecarrier block C and thereby substantially parallel with the axis of thetools D 1 and F when the latter are securely embraced in the block C asshown. The other external configuration of the carrier block C'maypreferably follow the shape disclosed in Figure 1 of the drawings, andis preferably of a size such that the carrier block C may be securelygrasped by human hands, such as with the bases of the palms, and perhapsalso the thumbs gripping the back face l4 thereof and-with the fingersextending around to engage the inclined faces 16 of the block C.

From the arrangement of parts shown in Figure 1 those skilled in the artwill understand that if the horizontal contour of the follower F, or atleast the portions thereof which contact the working contour I-l of thetemplate T, comprise a true vertical projection of the contour of thecutting face of the dressing tool D, and if the plane of the top surfaceof the block B and the bottom surface l5 of the block C is trulyhorizontal as shown in Figure 3, and the cutting edge of the dressingtool D is addressed to the grinding wheel W in the horizontal plane ofthe axis thereof, that the contour Il' of the template I may betransferred to the face of the grinding wheel W by sliding the block Caround on the upper face of the block B with the dressing tool 40.cutting thewheel W to the depth limited by contact between the feeler Fwith the template T. Since the block C rests freely upon the block B andthe same may be moved around within a wide angle whereby to accommodatethe follower 5 F to contact with the irregular contour l-I of thetemplate T, and at the same time to present the'dressin tool D to thewheel in precisely the same relation that the feeler addresses the template, that the wheel can be dressed to the same operative contour asthat possessed by the template.

The first step, therefore, in the practice of my invention is to formthe working end of the follower F to such a shape that when the partsare the follower F which contacts the contour ll of the template T willrepresent a true vertical projection of the outline of the cuttingsurface of the dressing tool D, i. e., in the form shown, the cuttingsurface of the diamond I i mounted therein. To this end I provide thatthe side wall I! of the block C lie at right angles to both the walls orsurfaces H and I5 thereof and in the position shown in Figure 1 trulyvertical and normal to the bottom surface l5 and the top surface 6 ofthe block B. I provide of course that the dressing tool D with itsdiamond or other cutter l I be such that it will cut or dress a grindingwheel, suchas a carborundum wheel, but that the follower F, preferablybeing of hardened steel, be of such material that it will be cut orabraded by the wheel or wheels which are capable of being cut or dressedby the dressing tool D.

. For the purpose of giving the desired contour 1 except for the groovesthereupon, comprises a assembled as shown in Figure 1, that portion ofexample,1ie horizontally, and which has a true rearward supporting edge20 against which the face ll 'of the block C may rest, whereby to alignthe block C on the chuck I8 with corresponding points of the tool D andfeeler F in a' plane normal to the axis of a grinding wheel 2| withrespect to which the block C may be moved in parallel relationship. Thatis, the block C supported on the chuck l8 or otherwise, as may be moreconvenient, is so supported as to be moved back and. forth in trueparallelism to a plane normal to the axis of the grinding wheel 2|, andis also so supported in the relationship shown in Figure- 2 that the.block as a whole maybe moved upwardly toward the axis of this grindingwheel in successive passes as the dressing tool D cuts into the-grindingwheel 2| to. give to the grinding wheel H a cutting'face or contour 22which is a true complement of the cutting edge of the dressing -tool D.The follower F in the first instance is formed with its Working end ofsuch shape 7 as to be greater in cross sectional area than the isbrought into contact with the samepoint or.

zone of the wheel 2 I in the same horizontal motion. The result is thatthe dressing tool first takes a cut from the face of the grinding wheel,giving it the operative shape and contour of so much of the dressingtool as has contacted therewith, and then the wheel in turn imparts thesame shape and contour to the working end of the follower F as it ispassed under the wheel 2| in the same relation thereto as the dressingtool D. A plurality of such passes of the block C with relation to thewheel 2! and the gradual raising of the block C, while maintaining it inthe same geometric relationship to the plane of the wheel 2|, ultimatelyimparts to the face of the wheel 2! the whole contour of the cuttingedge of the dressing tool and the wheel in turn imparts to the followerF the same contour, i. e.

relation to the body of the work, and that the template may preferablybe positioned on the base block B and both secured with the true backedge of the template parallel to the axis of the wheel W. Thus when thework is dressed by the dressed wheel it may be conveniently secured andmoved with relation thereto in 8. corresponding manner to receive thecontour from the dressed wheel in the same or other predeterminedrelation to its body or any trued surface thereof.

The wheel W may, of course, be rotatably supported and driven in asuitable frame 25 with appropriate bearings and otherwise, as iswellknown in the art, whereby to cause it to revolve about a true axis, andthe baseblock B, being secured to a support It, may be raised and low- Iand partly by the grip of the hands which guide it, being held in firm;even sliding engagement between its lower face I5 and the top face 8,the latter being kept clean for obvious reasons, and being largelyself-cleaning through the grooves in the surfaces thereof, whereby tomaintain the cutting edge of the dressing tool in direct verticalalignmentwith the corresponding contour of the follower F. As viewed inFigure 4 the carrier block C may be slid directly toward the grinding'wheel and template, and may be swung trans versely with respect to theplane of the grinding wheel more or less and as much as may be desired,consistent with presenting the cutting edge of the dressing tool to theworking face of the wheel and at the same time presentingthe working endof the follower tool to the contour 5-8 of the template T. In thismanner, as the carried blockC is slid over the face of the base block IB, and swung more or less transverselyof the a precise lineal projectionof the cutting edge of the dressing tool at right angles to the plane ofthe bottom face l5 of the carrier block 0.

Thereafter the carrier block is ready, when positioned upon the baseblock B, asshown in Figures 1, 3, 4 and 6, to be used for dressing-thegrinding wheel W. As shown particularly in Figures 3, 4 and 6 (having inmind that in Figure 3 the dressing tool is shown to the right of thewheel whereas in Figures 4 and 6 the dressing tool is shown to the leftof the wheel) the base block the dressing tool D'has its cutting edge inand movable in the horizontal plane of the axis of I the undressedcontour of the. face of the wheel.-

It will be understood as shown in Figure 4 that the contour l --l of thetemplate should preferably be related to the body thereof in the sameway that the contour is desired to be created in B is secured in suchrelation to the wheelW that.

plane of the grinding wheel, the whole cutting.

edge of the dressing tool may be advantageously employed to attackvarious faces of the grinding wheel in a manner which the operator mayfind most convenient. So long as the carrier block C'is caused to restin firm engagement with the top face of the base block B, the cuttingedge ot the dressing tool D cannot come nearer to the axis of thegrinding wheel than a true vertical projection ofthe contour ll of thetemplate T or any part thereof; and solong as the operv ator urges thecarrier block toward the grinding wheel and urges the follower tool intocontact with the template throughout the whole of the contour thereof,the wheel will be dressed until it corresponds precisely with thecontour of the template. During this operation the cutting edge of thedressing tool always is constrained to I move in the plane of the axisof the wheel (pref erably a horizontal plane asshown) parallel to theplane of the contour l--l of the template and normal to the lines ofprojection of corresponding points in the cutting .edge of the tool Dand feeler F. The finlshedsurfacebf the feeler F also moves in the planeof the contour I--l and parallel to the plane of motion of thecutting-edge of the dressing tool. v

At this-point it is well to mention that it is preferable that thecutting edge of the tool D and the corresponding face of the feeler Fproject not substantially farther from the face of the block C than isnecessary for convenient address of the feeler to the contour of thetemplate and the tool to the face of the wheel W. Thus the tendency ofthe tool to chatter or of the block C to tip or chatter relative to theblock B is held to a minimum.

As shown by way of illustration in Figures 4 and 6, the work K may, whenconvenient, be secured in position on the same table ID as that whichsupports the block B, so that after the wheel W is fully or partlydressed the work may be passed under the wheel to be given the contourof the dressed face of the Wheel by various or repeated passesthereunder, and particularly in those instances where new work is beingformed from fresh stock or a new wheel is being given its initial form,it may be desirable to do a rough job of wheel dressing and then a roughjob of forming the work in the first instance. In such a casethe'convenience of the arrangement shown in Figures 4 and 6 willbe'apparent since after the rough dressing and grinding has been done,the dressing equipment, comprising the blocks B and C with attendantparts above described, may again be brought to operative relationshipwith the wheel W, and the wheel re-dressed or given a finished dressingbefore completing the grinding of the work K.

It will, of course, be appreciated that the wheel may be dressed andre-dressed any number of times by positioning the dressing equipment inthe relationship indicated, and pro eding within the precepts describedabove. It will, of course, be understood that'whenever the contour ofthe dressing tool has become worn to an extent reater than the accuracyrequired in any particular job, that the carrier block C with its toolsF and D may be returned to the operation described with reference toFigure 2, and the follower tool re-formed to the altered'contour of thedressing tool, whereupon the parts will be ready again for dressing thewheel W. It will be further understood that the template T and thecontour thereof is only illustrative of any one of an infinite number ofcontours or templates that may be used, and that the fineness ornarrowness sake of convenience of description as well as for ordinaryconvenience of operation and use, referred to the vertical alignment ofthe points of the dressing tool with corresponding points on the feeler,and have indicated that the cutting edge of the dressing tool should liein the horizontal plane of the axis of the wheel to be dressed, as shownin Figs. 2 and 4, that the essential geometric relationship is notnecessarily limited to the vertical or horizontal as such, but on thecontrary those skilled in the art will understand that the essentialangular relationships may be retained if the departure from strictverticalness and horizontalness is made without altering the essentialgeometrical relationship of the parts to each other. For example, in thearrangement shown in Figure 3 the top surface of the base block B mightconceivably be inclined from the horizontal plane without departing fromthe precepts of my invention, so long as the plane of the surface 6 ofthe base block was parallel to the" axis of the wheel W and normal tothe lines oftangency from the face of the grinding wheel, which met thegrinding wheel at the point of contact with the dressing tool in theplane of the axis of the wheel W. As a result the point of contactbetween the dressing tool and the face of the grinding wheel would liein a line tangent to the dressing wheel, which line would also includethe corresponding point in the follower or feeler so that when the wheelwas finally dressed such a line of tangency would also embrace the pointof contact between the follower or feeler and the contour of thetemplate; the contour of the template lying in a plane parallel to thetop surface 6 of the block B, and also normal to the aforesaid line orlines of tangency to the face of the dressed wheel.

Similarly in the operation described with reference to Figure 2 thehorizontal disposition and motion of the block C might be altered solong as the dressing tool and the feeler contacted the wheel 2| withcorresponding points lying in the same plane normal to the axis of thewheel, and in the same line or lines tangent to the face of the wheel insaid planes.

I have indicateda preference for using hardened steel in the blocks Band C because, among of the cutting edge of the diamond or other"dressing tool with the corresponding fineness or narrowness of theworking end of the follower F should bear a reasonable relationship tothe nature of the contour l-l or the like in the template, i. e. wheresimple curved contours are to be developed in the dressing wheel, andare pro vided in'the template, then, of course, coarser and more roundeddressing tools and followers or feelers will be adequate and desirable,but that where sharper angles are formed in the contour .of thetemplate, the shape of the dressing tool and follower must be such as tofacilitate the following of allof'the details of the contour of thetemplate. In all events, the cutting point or cutting points of thedressing tool, being in direct lineal alignment, i. e. verticalalignment as shown herein, with corresponding points on the working endof the'follower, the contour of the template will be accuratelytranslated into the dressed face of the wheel to be dressed, care beingtaken that the shape of the dressing tool and follower is such as totraverse and contact all essential points of the contour of thetemplate.

Those skilled in the art will understand that while in the foregoingdescription I have, for the other reasons, I find that such materialaids in maintaining the mutual bearing surfaces thereof true and freefrom scratches or abrasions for a longer life. Other materials may 'ofcourse be used or found to have equal or better properties in respect tothe practice of my invention. The magnetic properties of hardened steelpermit the use of magnetic chucks, but of course the'practice of myinvention would not be enhanced by binding the block C'to the block B bymagnetism or otherwise to substantially interferewith the intendedfreedom of movement of one block relative to the other.

While I'have illustrated and described a preferred embodiment of themethod and means to which my invention pertains, numerous modificationsand changes therein will occur to those skilled in the art, all withinthe major precepts of my invention, and I do not care to be limited inthe scope of my patent to the particular or preferred form hereindisclosed, or in any manner other than by the claims appended heretowith their full range of equivalents to which they are entitled in viewof the state of the A a desired contour comprising, a base member, atemplate mounted thereon having a predetermined contour at one edge tobe reproduced in the peripheral face of a grinding wheel, a memherhaving a base adapted to be moved horizontally over the upper side ofthe first mentioned base in any direction, a holder for a wheel dressingimplement connected with and located above said second base, aldressingimplement carried by said holder, said wheel dressing implement beingadapted to be pointed toward and located in the same horizontal planewith the axis about which the grinding wheel to be dressed rotates, anda feeler mounted on said second base adapted to be brought against thecontour edge of said template, said feeler having a feeler contact pointin direct vertical alignment with the point ofsaid dressing implement,and having sides corresponding to the sides of said dressing implement,as and'for the purposes specified.

2. Apparatus for shaping the peripheral face of a grinding wheel to adesired contourco'mprising, a base member having a'flat upper side, atemplate secured at the forward end and above said base member, saidtemplate being positioned 5: a carrier block slidably supported uponsaid base member and rigidly carrying a wheel dressing tool disposed tocontact the wheel in the plane of theaxis thereof parallel to said firstnamed plane and in any angular relation to the plane of the wheel, atemplate having a contour to be reproduced in said wheel fixedly securedto said base block with the contour lying in a plane parallel to thesaid first named plane and intersecting lines tangent to the finallydressed face of the wheel where said cutting tool has' contacttherewith, and a feeler rigidly carried by said carrier block positionedto have contact with the contour of said template, all points in saidfeeler having contact with said contour lying in the projection ofcorresponding points in the cutting edge of said dressing tool at rightangles to said plane. g

5. Grinding wheel dressing mechanism comprising in combination a basemember adapted to be held in fixed relation to the axis of the wheel tobe dressed and having a supporting surface adapted to cause a body movedthereover substantially horizontal and having its rear edge shaped inaccordance with a desired contour to be given to a grinding wheel, amember including a base structure having a fiat under side adapted to bemoved slidably over the upper side of the first base member in anydirection, a post extending upwardly from said second base, ahorizontally located dressing tool holder carried by said post andextending in a forward direction, a dressing tool carried by saidholder, having a head with a dressing point at the front end thereof, afeeler adjustably mounted at the upper side of said. second base memberhaving a pointed front end portion, the end of which is in directvertical alignment with the front end of the dressing tool and havingsides corresponding to the sides of said dressing tool, said feeler atits forward end being adapted to follow the contouor at the rear edge,of said template, as specified.

3. Apparatus for shaping grinding wheelsto a desired contour comprising,a base member having a flat horizontal upper side, a horizon-'tally'disposed template mounted on and above said base at one endthereof having an edge a fiatunder side adapted to rest upon and moveover the upper side of the first mentioned base in any direction, aholder for a wheel dressing implement connected with and locatedabovesaid second base, a wheel dressing implement secured in said holderadapted to be pointed toward and have its dressing end lie in the samehorizontal plane with the axis about which the grinding wheel to bedressed rotates, and a feeler-mounthorizontal plane'with said template,said feeler having a free end to bear against the template and followthe contour thereof, the point of ento be, held in fixed relation to theaxis of the ed on-said second baseln substantially the same in slidingcontact to move upon a plane disposed parallel of the axis of the wheelto be dressed, a carrier block of substantial mass slidably supportedupon said base member and rigidly carrying a wheel dressing tooldisposed in the plane of the axis of the wheel parallel to said firstplane, a template having a contour to be reproduced in said wheelfixedly secured to said base block with the contour substantiallyparallel to the said plane and intersecting lines tangent to the finallydressed face of the wheel where said cutting tool has contact therewith,and a feelerrigidly carried by said carrier block positioned to havecontact with the contour of said template along points in its workingfacewhich lie in lines embracing corresponding points on the cuttingedge of said dressing tool and parallel to said tangents saidcarrier'block with its tool and feeler being free to assume any anglerelative to the plane of the wheel to .be dressed and to swing about thepoint of contact of the tool with the wheel as a center.

6. Mechanism for the dressing of grinding which lie in correspondingpoints in the cutting edge ofvsaid dressing tool and the working face ofsaid follower tool, said block also having a supporting face at rightangles to said first named face and parallel to said lines, saiddressing tool being hard enough to cut or abrade a grinding wheel, andsaid follower tool being of hardness such that it in turn .can beabraded by the same grinding wheel when supported on said second namedsurface and moved in said lines.

'7. A wheel dresser comprising a dressing tool having a cutting edge,means for supporting said tool in dressing relation to the face of saidwheel in the plane of the axis thereof and permitting said' tool toswing about its cutting edge as a wheel to be dressed and having 'asupporting surface adapted to cause a body moved thereover in slidingcontact to moveupon a plane parallel of the axis of the wheel to bedressed,

center, a template having the contour to which said wheel is to bedressed, and means havin a surface the replica of the cutting edge ofsaid tool engageable with said contour mil-312E 25 with said first namedmeans for restraining the cutting edge of. said dressing tool frommovementbeyond said contour but in any angular relation thereto, saidcontour being disposed in the tangential projection of the face of saidwheel from the point of contact of said dressing tool therewith.

'8. Apparatus according to claim 1 in which said bases have limitedspaced areas of contact separated by grooves in the bearing surface ofat least one of said members. I

9. Mechanism for dressing grinding wheels, comprising a carrier blockrigidly supporting a wheel dressing tool and a follower or feeler andadapted to be moved so that the dressing tool will bear upon the face ofthe grinding wheel and the follower tool will bear upon a templatehaving the contour to be developed'in said wheel, said carrier blockhaving one substantially planar surface with its bearing points defininga plane normal to lines which lie in corresponding points in the cuttingedge of said dressing tool and the working face of said followertoolfisaid block being movable on said plane to swing said tool aboutits cutting edge as a center and means for supporting said block forfree movement in any direction on said plane.

10. The mechanism of claim 5 in which the contacting surfaces of saidbase member and carrier block are each grooved to-provide a plurality ofnarrow lands, those in the base member lying transversely to those inthe carrier block when the carrier block is at a substantially neutralangular position relative to the plane of the wheel whereby the block issupported on the member at a plurality of points of limited area whichhave self cleaning sliding contact upon sliding movement of said blockrelative to said member.

11. The combination of claim 7 in which said. v first named meansincludes a fixed member having bearing surface exposed to grit and dustfrom said wheel and a moveable member slideably sup ported thereupon,and means for excluding such grit and dust from said surface.

12. The mechanism of claim 9 in which said carrier block has partsdefining a plane disposed at right angles to said substantially planarsurface and disposed oppositely of said dressing tool and follower.

13. The mechanism defined in claim 9 in combination with means forcleaning said last named means of extraneous matter coming in contacttherewith.

JOHN SNEED.

